Commit 4781d633 authored by Vladis Dronov's avatar Vladis Dronov Committed by Kamal Mostafa

ALSA: usb-audio: Fix double-free in error paths after snd_usb_add_audio_stream() call

commit 836b34a9 upstream.

create_fixed_stream_quirk(), snd_usb_parse_audio_interface() and
create_uaxx_quirk() functions allocate the audioformat object by themselves
and free it upon error before returning. However, once the object is linked
to a stream, it's freed again in snd_usb_audio_pcm_free(), thus it'll be
double-freed, eventually resulting in a memory corruption.

This patch fixes these failures in the error paths by unlinking the audioformat
object before freeing it.

Based on a patch by Takashi Iwai <tiwai@suse.de>

[Note for stable backports:
 this patch requires the commit 902eb7fd ('ALSA: usb-audio: Minor
 code cleanup in create_fixed_stream_quirk()')]

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1283358Reported-by: default avatarRalf Spenneberg <ralf@spenneberg.net>
Signed-off-by: default avatarVladis Dronov <vdronov@redhat.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
parent d16c2798
...@@ -147,6 +147,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, ...@@ -147,6 +147,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip,
usb_audio_err(chip, "cannot memdup\n"); usb_audio_err(chip, "cannot memdup\n");
return -ENOMEM; return -ENOMEM;
} }
INIT_LIST_HEAD(&fp->list);
if (fp->nr_rates > MAX_NR_RATES) { if (fp->nr_rates > MAX_NR_RATES) {
kfree(fp); kfree(fp);
return -EINVAL; return -EINVAL;
...@@ -190,6 +191,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip, ...@@ -190,6 +191,7 @@ static int create_fixed_stream_quirk(struct snd_usb_audio *chip,
return 0; return 0;
error: error:
list_del(&fp->list); /* unlink for avoiding double-free */
kfree(fp); kfree(fp);
kfree(rate_table); kfree(rate_table);
return err; return err;
...@@ -465,6 +467,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip, ...@@ -465,6 +467,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip,
fp->ep_attr = get_endpoint(alts, 0)->bmAttributes; fp->ep_attr = get_endpoint(alts, 0)->bmAttributes;
fp->datainterval = 0; fp->datainterval = 0;
fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize); fp->maxpacksize = le16_to_cpu(get_endpoint(alts, 0)->wMaxPacketSize);
INIT_LIST_HEAD(&fp->list);
switch (fp->maxpacksize) { switch (fp->maxpacksize) {
case 0x120: case 0x120:
...@@ -488,6 +491,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip, ...@@ -488,6 +491,7 @@ static int create_uaxx_quirk(struct snd_usb_audio *chip,
? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK; ? SNDRV_PCM_STREAM_CAPTURE : SNDRV_PCM_STREAM_PLAYBACK;
err = snd_usb_add_audio_stream(chip, stream, fp); err = snd_usb_add_audio_stream(chip, stream, fp);
if (err < 0) { if (err < 0) {
list_del(&fp->list); /* unlink for avoiding double-free */
kfree(fp); kfree(fp);
return err; return err;
} }
......
...@@ -315,7 +315,9 @@ static struct snd_pcm_chmap_elem *convert_chmap(int channels, unsigned int bits, ...@@ -315,7 +315,9 @@ static struct snd_pcm_chmap_elem *convert_chmap(int channels, unsigned int bits,
/* /*
* add this endpoint to the chip instance. * add this endpoint to the chip instance.
* if a stream with the same endpoint already exists, append to it. * if a stream with the same endpoint already exists, append to it.
* if not, create a new pcm stream. * if not, create a new pcm stream. note, fp is added to the substream
* fmt_list and will be freed on the chip instance release. do not free
* fp or do remove it from the substream fmt_list to avoid double-free.
*/ */
int snd_usb_add_audio_stream(struct snd_usb_audio *chip, int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
int stream, int stream,
...@@ -668,6 +670,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no) ...@@ -668,6 +670,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
* (fp->maxpacksize & 0x7ff); * (fp->maxpacksize & 0x7ff);
fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no); fp->attributes = parse_uac_endpoint_attributes(chip, alts, protocol, iface_no);
fp->clock = clock; fp->clock = clock;
INIT_LIST_HEAD(&fp->list);
/* some quirks for attributes here */ /* some quirks for attributes here */
...@@ -716,6 +719,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no) ...@@ -716,6 +719,7 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
dev_dbg(&dev->dev, "%u:%d: add audio endpoint %#x\n", iface_no, altno, fp->endpoint); dev_dbg(&dev->dev, "%u:%d: add audio endpoint %#x\n", iface_no, altno, fp->endpoint);
err = snd_usb_add_audio_stream(chip, stream, fp); err = snd_usb_add_audio_stream(chip, stream, fp);
if (err < 0) { if (err < 0) {
list_del(&fp->list); /* unlink for avoiding double-free */
kfree(fp->rate_table); kfree(fp->rate_table);
kfree(fp->chmap); kfree(fp->chmap);
kfree(fp); kfree(fp);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment